Physical vapor deposition (PVD) is commonly used within the semiconductor industry as well as within solar, glass coating, and other industries, in order to deposit a layer over a substrate. Sputtering is a common physical vapor deposition method, where atoms or molecules are ejected from a target material by high-energy particle bombardment and then deposited onto the substrate.
In order to identify different materials, evaluate different unit process conditions or parameters, or evaluate different sequencing and integration of processes, and combinations thereof, it may be desirable to be able to process different regions of the substrate differently. This capability, hereinafter called “combinatorial processing,” is generally not available with tools that are designed specifically for conventional full substrate processing. Furthermore, it may be desirable to subject localized regions of the substrate to different processing conditions (e.g., localized deposition) in one step of a sequence followed by subjecting the full substrate to a similar processing condition (e.g., full substrate deposition) in another step.
Current full-substrate PVD tools used in the semiconductor industry have a large sputtering source including a large sputtering target, i.e., the target is larger than the substrate in order to deposit a uniform layer on the substrate, even for substrates as large as 300 mm wafer. Alternatively, some full substrate PVD tools use a smaller sputtering source, e.g., 3″ or 4″ diameter target, and rotate the wafer in order to deposit a uniform film, where the substrate may be 200 mm diameter or smaller, and the sputtering source is pointed to approximately the mid-radius of the substrate. In these methods, the target-to-substrate spacing is relatively large, e.g., 200 mm, requiring significant space between the sputtering source and the substrate in order to deposit a uniform film on the full substrate.
Combinatorial processing chambers typically include smaller sputtering sources. However, deposition rates can suffer. A plurality of small sputtering sources aimed at a common location on a substrate must be positioned at a significant distance from the substrate to ensure good uniformity of the deposited film within an isolated spot. Particularly for thick film applications such as the formation of metal and metal nitride electrodes, process times of several hours are common. Significant contamination and poor film quality are common byproducts of long processing time.